Changing the distance between vanishing points
Set the Focal Length to a smaller value to adjust the perspective.

The Focal Length can be set separately for any Camera as well as for the Viewport. To adjust the Viewport, simply open the Properties panel of the 3D Viewport (press N) and scroll down to View as shown and change the 'Lens' setting.

For the Camera, select the Camera and open the Camera properties panel and change the Focal Length as desired.